Multi-stage compressor



June 9, 1964 A. J. NICHOLAS MULTI-STAGE COMPRESSOR 4 Sheets-Sheet 1Filed March 28, 1961 ANDREW I NlC l l g j fis gywfl' June 9, 1964 A. J.NICHOLAS 3,136,477

MULTI-STAGE COMPRESSOR Filed March 28, 1961 4 Sheets-Sheet 2 ANDREW J.NICHOLAS INVENTOR.

4 Sheets-Sheet 3 Filed March 28, 1961 FIG.6

ANDREW J'. NICHOLAS J1me 1964 A. J. NICHOLAS MULTI-STAGE COMPRESSOR 4Sheets-Sheet 4 Filed March 28, 1961 FI GB SMJ/ LM ANDFQEW J. NICHOLAS e-e FIGJO 4 United States Patent Oflice 3,136,477 Patented June 9, 19643,136,477 MULTI-STAGE COMPRESSOR Andrew J. Nicholas, Sufiield, Conn.,assignor to Worthington Corporation, Harrison, N.J., a corporation ofDelaware Filed Mar. 28, 1961, Ser. No. 98,914 8 Claims. (Cl. 23040) Thisinvention relates to multi-stage compressors and is an improvement ofthe unit shown in the copending application of Henri Soumerai SerialNumber 63,045 filed October 17, 1960, now abandoned, for a .compressorincluding means for converting a multi-cylinder unit to multi-stageoperation.

To this end the unit disclosed in the above application provides a highpressure stage in the usual multi cylinder unit with the incorporationof a sealing member and a plate like structure which directs fluidcompressed by the low pressure stage to the suction inlet of the highpressure stage.

It has been found that an arrangement of the plate like structure as isdisclosed in above patent application does not provide or permit thenecessary inter-cooling, for optimum compressor operation, of the fluidpassing from the discharge of the low pressure stage to the inlet of thehigh pressure stage.

Accordingly it is an object of this invention to provide means forconverting a multi-cylinder compressor to multistage operation whichentails providing a minimum of modified components for themulti-cylinder unit including cooling means arranged to inter-cool fluidpassed from the discharge of the low pressure stage to the inlet of thehigh pressure stage.

It is another object of the present invention to provide 'an unloadermeans for use with the multi-stage compressor which has relatively fewparts and hence can be manufactured at less cost, and is adaptable forassembly in a unit including a cooling means.

It is a further object of this invention to provide an improvedmulti-stage compressor including means for varying the capacity thereofwhich is simple in construction.

i It is another object of this invention to convert a multicylindercompressor to multi-stage operation without costly redesign.

Other objects and advantages of the invention including the basic designand the nature of the improvements thereon will appear from thefollowing description taken in connection with the following drawings;in which:

FIGURE 1 is a side view of an unconverted compressor.

FIGURE 2 is an end view of an unconverted compressor.

FIGURE 3 is a perspective view of an unconverted compressor with acylinder head partly broken away.

FIGURE 4 is a vertical section through a cylinder head of an unconvertedcompressor showing the unloader means associated therewith.

FIGURE 5 is a schematic view of a converted compressor of the type shownin FIGURE 3.

FIGURE 6 is a fragmentary vertical section through the convertedcylinder head of the compressor schematically shown in FIGURE 5 FIGURE 7is an enlarged exploded view partly in section and partly in perspectiveof the liner and piston portion of the conversion kit.

FIGURE 8 is a plan view of the plate portion of the conversion kit.

FIGURE 9 is a side view of the plate shown in FIGURE 8.

FIGURE 10 is an end view of the plate shown in FIGURES 8 and 9.

Unconverted Multi-Cylinder Compressor Referring to the drawings FIGURES1 through 4 show the unconverted multi-cylinder refrigeration compressorgenerally designated U-l contemplated for conversion to a multi-stageunit as will be described in detail hereinafter. For purposes of clarityand in order to facilitate the comprehension of the concepts of theadvance described herein, parts having generally the same constructionand purpose will be given the same reference characters. However, inorder to distinguish the units reference characters applied to theunconverted unit will be preceded by a U and those applied to aconverted unit will be preceded by a C.

Continuing with the presentation of the construction of compressor U-l:the unit comprises a driving portion U-2 (which may be any known primemover such as an electric motor) and a compression portion U-3 shown asincluding a plurality of compression means U-4 which compress fluidpassed to the suction opening U-5 from the low side of a refrigerationinstallation and discharge this fluid out discharge opening U-6 to thehigh side of a refrigeration installation.

While the plurality of compression means U-4 are shown as comprising 4banks each including 2 cylinders designated U-7, it is not intended tolimit the scope of this invention to this arrangement as any number ofbanks within the realm of reasonableness may be provided. It will alsobe understood by those skilled in the art that the conversion means, tobe hereinafter described, for embodiment in the multi-cylinder type ofcompressor to convert same to multi-stage operation may be adapted to amulti-cylinder compressor including single cylinders without departingfrom the scope of the improvement contemplated herein. It will also beevident that the disclosed invention is as applicable to hermetic typecompressors.

Referring to FIGURES 3 and 4, the compression portion U-4 of the unitincludes a casing U-8 which is divided by a partition U-9 to provide afirst and second compartment U-10 and U-11. In actual constructioncompartments U-10 and U-11 are cast as separate portions of the casingto provide chambers which are respectively connected to the low and highside of the system.

More particularly compartment U-10 is in communication with suctionopening U-5 which is in turn connected to the low side of therefrigeration system.

Compartment U-11 receives compressed fluid from the compression meansU-4 through passage or opening U-12 and passes this pressurized fluid tothe high side of the system through discharge opening U-6.

As is customary in this type of unit, the compression means U-4 all takesuction from the first compartment U-10, and as will be understood bythose skilled in this art fluid passes through a port U-13 formed inliner U-14 into cylinder U-15. The usual suction valve U-16 is disposedover port U-13 to regulate flow into and out of cylinder U-15. PistonU-17 driven through usual crank shafts by driving means U-2 compressesthe fluid and forces same through the discharge port U-18 by dischargevalve U-19, all of which are disposed in valve plate U-20 and valveguard U-Zl, into discharge chamber U-ZZ.

Discharge chamber U-22 is shown as formed by disposing means comprisinga head U 23 on a portion of casing U-8 which communicates with thesecond compartment U11 through opening U-12. Fluid passed to compartmentU-11 is discharged through discharge opening U-6 to the high side of thesystem.

In order to operate the compressor at substantially constant speed butat increments of its full capacity, means taking the form of a moveableannular element U-24 is disposed about the cylinder and in closeclearance with a boss U-25 formed on the cylinder liner U-25' and insuch fashion as to provide a chamber U-26 therebetween. Seal means U-27and U-2j8, shown as O-rings are disposed in grooves formed in themoveable element and the boss to coact with the liner and the moveableelement to confine fluid passed to chamber U-26 therein.

The moveable element U-24 is normally held in abutment with flange U-29formed as an extension of the liner U-ZS' by resilient means (not shown)disposed in an opening in the bottom portion of the moveable elementU-24 and in engagement with the lower bulk head of the compressionmeans.

During the stage of compressor operation when element U-24 is inabutment with the flange portion U-29, it functions to preclude passageof gas from the suction compartment U- to cylinder U- through chamberU-13.

The moveable element is guided and aligned during assembly of thevarious elements by a fluid connecting means U-30 which is incommunication with the fluid type chamber U-26 at one end and a sourceof fluid such as the lubrication system of the compressor at the otherend.

When proper conditions occur or when desired, fluid is passed from thesource (not shown) to the fluid tight chamber U-26 to move the moveableelement U-24 downwardly and thereby open communication between thesuction compartmentU-10 and the cylinder.

While only one bank is described it will be evident to one skilled inthe art that the remaining banks of the unconverted compressor U-l areof similar construction and function in the manner described above Thecompressor U-l generally described above can readily be adapted tomulti-stage operation should a particular refrigeration system requiresame. Thusly the above described unit may be converted to multi-stageoperation as hereinafter described without the need for complicated andcostly redesign.

Conversion Means The desired conversion to multi-stage operation is ac-.

complished by associating conversion means generally designated 0-50with at least one bank of the multicylinder compressor described above.

Accordingly in this manner the remaining unconverted stages will act asa low pressure stage and provide the initial increase in pressure to thefluid which is then raised to the final or output pressure by theconverted or high pressure stage as will be evident from the descriptionthat follows. And with the advance contemplated herein the fluid passingfrom the low pressure stage to the inlet of the high pressure stage iscooled to thereby provide a more eflicient compressor.

With more particularity the conversion means C-St) comprises a platemeans C-51, having a frusto like opening C-52 and forming a dischargechamber C-53, which is mounted in association with cylinder liners C-54.The liners C-54 form cylinders C-93 and are distinguishable from thoseshown in connection with the low pressure stages in FIGURES l to 4 inthe flange means C-55 is seated on the top portion of bulkhead C-56 andis machined to form a seat C-57 for the discharge valves C-58.

Plate means C-51 is counter bored as at C-59 and provided with a seriesof drilled holes C-6tl which receive springs C-61 acting'to keep thedischarge valve on its seat.

A gasket C-62 is disposed between the flanges and bulk head andfunctions to seal the cylinder from the suction compartment 0-10.Passage means comprising spaced cut-outs C-63 and recessed pocket C-64connect the cylinder through discharge valve C-58 with the dischargechamber C-53.

forming to the shape of opening C-SZ is disposed within the cylinder toact as usual on the fluid to be compressed.

A second plate C- forming a suction and cooling compartment C-71 isdisposed over the discharge plate C-51. The plates C-70 and 0-51 areconnected to the casing of the compressor by any well known means suchas by bolt members (3-72.

The suction compartment 0-71 is connected to the second compartment C-llthrough a passage way C-73 formed in the plate C-51 and segregated fromthe discharge chamber C-53.

Controlling the superheat of the gases discharged from the low pressurestages and collected in the second compartment C-ll is accomplished withthe provision, in plate means C-70, of cooling fins C-74 and coolingpassages C-75 which are shown as cast water or other cooling mediumpassages which may be connected to a source of cooling fluidnot shown.

The head portion and suction valve cage of the cylinders comprising thehigh pressure stage are formed by the body portion C- of the unloaderelement generally designated C-8l. A flange C-82 formed on the lower endof the body portion (3-80 is seated on the top portion C-83 of thedischarge plate C-51 and is provided with a seat C-84 for the ring typesuction valve C-SS.

Counter-bore 0-86 and drilled holes C-87 are formed in the plate C-Sl toreceive spring means C-88 and provide the clearance space and seatingfunction for the suction valve in similar fashion as was described aboveregarding the discharge valves. A Belville washer C-89 firmly positionsthe body portion C-80 of the unloader means on the plate means C-51 andcoacts therewith to form an operative cylinder.

In order to compensate for the small clearance between the head portionof the piston and the opening 0-52, peripheral grooves C-90 are formedin the truncated portion C-66 of piston C-65 and terminate in ahorizontal groove C-91 formed therein. It will be evident that at toppiston dead center the groove C-91 aligns itself with the slots in theliner C-63 to permit free flow of compressed fluids out discharge valve0-58.

The usual sealing means are provided to maintain fluid type relationshipbetween the various chambers described hereinabove.

In order to operate the multi-stage compressor at substantially constantspeed but at increments of its full capacity, means taking the form of amoveable annular element C- is disposed about the body portion C-8t) andin close clearance with the boss 6-101 formed thereon and in suchfashion as to provide a fluid type chamber C-102 therebetween. The usualseal means such as O-rings are disposed in the boss and moveable elementto coact with the liner and the moveable element to confine fluidpassedto chambers (3-102 therein.

The moveable element C-100 is normally held in abutment with flange C-82formed on the body portion C-Stl by spring means C-103 disposed in anopening C-104 in the top portion of moveable element C-ltltl.

. During the stage of compressor operation when the moveable elementC-100 is in abutment with the flange portion C-SZ as is shown in FIGURE6, it functions to preclude passage of gas'from the second compartmentC-ll to cylinder C-93 through the suction valve C-35.

The moveable element is guided and aligned during assembly of variouselements by a fluid connecting means C-106 which is in communicationwith the fluid type chamber C-102 at one end and a source of fluid suchas the lubrication system of the compressor at the other end.

When proper conditions occur or when desired, fluid is passed from thesource of the fluid type chamber to thereby actuate the moveable elementout of engagement with the flange C-82 and open communication betweenthe suction compartment C-71 and the cylinder to be acted upon therebyand then discharged out of discharge opening -107 to the installationincluding this multistage compressor.

Operation of the Converted Compressor In operation of the multi-stageunit, low pressure gas from the system enters the first compartment C-10through the opening C in the casing C-8. Gas from the first compartmentpasses through the inlets of low pressure banks for compression by theusual pistons. Sealing means formed on the high pressure stage preventsthe passage of gas from compartment C- to the high pressure bank.

The gas compressed by the low pressure stages is discharged through theusual valving into the second compartment C-11 and flows through theports of passageway C-73 to the suction compartment C-71 as is clearlyshown in FIGURES 5 and 6.

Gas or fluid in the second compartment C-11 passes through to thesuction compartment C-71 and through the suction valve C85 into thecylinder of the high pressure stage and is acted thereon by the pistonand compressed to the desired pressure.

The gas is then discharged through discharge valves C-58 into thedischarge passage C-53 formed in plate C-51 and out discharge openingC-107 to the high side of the system.

Desired compressor capacity variation can be accomplished by loading orunloading the cylinders of either the low pressure or high pressurestage or stages. Furthermore by maintaining the cylinders in an unloadedcondition on start-up usual wear can be considerably reduced as isevident to those skilled in the art.

As was mentioned above that While the unit shown in the drawings anddescribed hereinabove comprises a two stage compressor including pluralcylinders in each stage it will be obvious that the multi-stagecompressor can be furnished in other forms by merely adding valve platesand sealing arrangements to a 10W stage thereof. Furthermore, amulti-cylinder unit comprising stages including one cylinder can beconverted to multi-stage operation in accordance with the conceptsdiscussed herein.

Although the invention has been described with reference to specificapparatus it will be appreciated that a wide variety of changes may bemade Within the ability of one skilled in the art without departing fromthe scope of this invention. For example, some of the components of theapparatus may be reversed, certain features of the invention may be usedindependently of others, and equivalence may be substituted for theapparatus, all within the sphere and scope of the invention as definedin the claims.

What is claimed is:

1. In combination with a compressor including a casing havingcompression chambers connected to compress a fluid through a singlestage of compression to a low pressure, at least one of said compressionchambers being operable at a second pressure higher than the pressure insaid remainder of said compression chambers and forming a high pressurestage, each of said compression chambers having a piston reciprocablyguided therein:

(A) said remainder of the compression chambers including:

(a) inlet means communicated with a source of the fluid,

(b) a low pressure manifold,

(c) discharge means communicating said remainder of said compressionchambers to said low pressure manifold,

(B) a conversion assembly carried on the casing and cooperative withsaid at least one compression chamber, and being in communication withthe low pressure manifold to receive fluid from the latter, saidconversion assembly including:

(a) means forming a cooling compartment having an inlet and outlet,

(b) means forming a passage communicating said inlet in said meansforming the cooling compartment with the low pressure manifold fordirecting compressed fluid into said cooling compartment prior tointroduction thereof to said at least one compression chamber,

(0) means in the conversion assembly forming an opening disposedcooperatively with the reciprocably guided piston in said at least onecompression chamber,

(d) said last mentioned means forming an opening including, meansforming a passage having a valved inlet and a valved discharge portcommunicating therewith, and

(C) unloader means positioned in the conversion assembly cooperativewith said valved discharge port to regulate passage of compressed fluidpassing therethrough.

2. In combination with a compressor including a casing havingcompression chambers connected to compress a fluid through a singlestage of compression to a low pressure, at least one of said compressionchambers being operable at a second pressure higher than the pressure insaid remainder of said compression chambers and forming a high pressurestage, each of said compression chambers having a piston reciprocablyguided therein:

(A) said remainder of the compression chambers including:

(a) inlet means communicated with a source of the fluid,

(b) a low pressure manifold,

(c) discharge means communicating said remainder of said compressionchambers to said low pressure manifold,

(B) a conversion assembly carried on the casing cooperative with said atleast one compression chamber, and being in communication with the lowpressure manifold to receive fluid from the latter, said conversionassembly including:

(a) means forming a cooling compartment having an inlet and outlet,

(b) a plate having a first side sealably engaging the casing and havingmeans forming a transverse opening extending through the plate slidablyreceiving at least a portion of a reciprocably guided piston,

(c) valve means positioned at the side of the plate sealably engagingthe casing, and being communicated with said means forming a transverseopening thereby defining a discharge valve for said at least onecompression chamber,

(d) means at the side of the plate remote from the casing forming avalved passage communicating the means forming the cooling compartmentwith said at least one compression chamber, and

(C) unloader means positioned in the conversion assembly cooperativewith said valved passage communicating the means forming the coolingcompartment with said at least one compression chamber.

3. In the combination defined in claim 2, wherein the unloader meansdefines a head portion at the upper surface of said plate in at leastone compression chamber and provides a closure to said means forming atransverse opening.

4. In the combination defined in claim 2, wherein the unloader meanspositioned in the conversion assembly is operable to disconnect themeans forming a cooling compartment from said at least one compressionchamber.

5. In the combination defined in claim 2, wherein the means at the sideof said plate remote from the casing forming a valved passage includes:

(A) means forming an annular channel in said plate surface opening intosaid at least one compression chamber, and being communicated With saidmeans forming a cooling compartment to pass fluid from said meansforming a cooling compartment into said at least one compressionchamber, and

(B) a valve member operably positioned in said means forming an annularchannel and being normally biased to prevent fluid flow to said at leastone compression chamber.

6. In the combination defined in claim 2 wherein said means forming atransverse opening in the plate is formed in a frustro-conical-likeconfiguration, and the portion of said reciprocably guided pistonreceived in said transverse opening includes an outer Wall formed in afrustro-conicallike configuration having a plurality of longitudinallyextending slots therein.

7. In the combination defined in claim 5 wherein said unloader means isoperable With the means atthe side of said plate remote from the casingforming a valved passage, to discontinue the flow of fluid from saidmeans forming a cooling compartment to said at least one com pressionchamber.

8. In the combination defined in claim 5 wherein the unloader meansincludes:

(A) an unloader member received in the means forming anannular channelin said plate surface, said unloader member being biased toward theplate surface therein forrning a fluid tight seal therewith,

(a) means forming a passage in said unloader member communicating themeans forming a cooling compartment with said at least onecompression'chamber,

(B) said valve member being operably positioned in the annular channeland normally biased into sealing contact withthe unloader member tocontrol flow of fluid from the means forming a cooling compartmentthrough said annular passage into said at least one compression chamber.7

References Cited in the file of this patent UNITED STATES PATENTS460,696 Windhausen Oct. 6, 1891 7 706,979 Martin Aug. 12, 1902 740,133Hildebrand Sept. 29, 1903 1,632,841 Le Valley June 21, 1927 1,736,469Swanson Nov. 19, 1929 2,141,069 Newell Dec. 20, 1938 2,168,036 ManiscaloAug. 1, 1939 2,575,241 White Nov. 13, 1951 2,576,876 Gamble Nov. 27,1951 2,955,750 Phelps Oct. 11, 1960 2,955,751 Hackbart et al. Oct. 11,1960 2,956,729 Nicholas Oct. 18, 1960

1. IN COMBINATION WITH A COMPRESSOR INCLUDING A CASING HAVINGCOMPRESSION CHAMBERS CONNECTED TO COMPRESS A FLUID THROUGH A SINGLESTAGE OF COMPRESSION TO A LOW PRESSURE, AT LEAST ONE OF SAID COMPRESSIONCHAMBERS BEING OPERABLE AT A SECOND PRESSURE HIGHER THAN THE PRESSURE INSAID REMAINDER OF SAID COMPRESSION CHAMBERS AND FORMING A HIGH PRESSURESTAGE, EACH OF SAID COMPRESSION CHAMBERS HAVING A PISTON RECIPROCABLYGUIDED THEREIN: (A) SAID REMAINDER OF THE COMPRESSION CHAMBERSINCLUDING: (A) INLET MEANS COMMUNICATED WITH A SOURCE OF THE FLUID, (B)A LOW PRESSURE MANIFOLD, (C) DISCHARGE MEANS COMMUNICATING SAIDREMAINDER OF SAID COMPRESSION CHAMBERS TO SAID LOW PRESSURE MANIFOLD,(B) A CONVERSION ASSEMBLY CARRIED ON THE CASING AND COOPERATIVE WITHSAID AT LEAST ONE COMPRESSION CHAMBER, AND BEING IN COMMUNICATION WITHTHE LOW PRESSURE MANIFOLD TO RECEIVE FLUID FROM THE LATTER, SAIDCONVERSION ASSEMBLY INCLUDING: (A) MEANS FORMING A COOLING COMPARTMENTHAVING AN INLET AND OUTLET, (B) MEANS FORMING A PASSAGE COMMUNICATINGSAID INLET IN SAID MEANS FORMING THE COOLING COMPARTMENT WITH THE LOWPRESSURE MANIFOLD FOR DIRECTING COMPRESSED FLUID INTO SAID COOLINGCOMPARTMENT PRIOR TO INTRODUCTION THEREOF TO SAID AT LEAST ONECOMPRESSION CHAMBER, (C) MEANS IN THE CONVERSION ASSEMBLY FORMING ANOPENING DISPOSED COOPERATIVELY WITH THE RECIPROCABLY GUIDED PISTON INSAID AT LEAST ONE COMPRESSION CHAMBER, (D) SAID LAST MENTIONED MEANSFORMING AN OPENING INCLUDING, MEANS FORMING A PASSAGE HAVING A VALVEDINLET AND A VALVED DISCHARGE PORT COMMUNICATING THEREWITH, AND (C)UNLOADER MEANS POSITIONED IN THE CONVERSION ASSEMBLY COOPERATIVE WITHSAID VALVED DISCHARGE PORT TO REGULATE PASSAGE OF COMPRESSED FLUIDPASSING THERETHROUGH.